1. Field of the Invention
The present invention relates generally to oil burning devices used to power low-pressure boilers, heating systems and the like, and more specifically to an oil burner configuration that allows for the burning of oils of varying viscosity while minimizing problems caused by sludge formation and clogging that are typical of conventional high viscosity and waste oil burning devices.
2. Description of the Related Art
In the United States alone, billions of gallons of waste oil are generated each year. Disposal of this oil is both costly and environmentally hazardous. While waste oil can be recycled and re-used for a variety of purposes, the process is complex, costly and nevertheless results in some quantity of non-recoverable materials that must be disposed of, posing the same environmental and health concerns as the outright disposal of the waste oil itself. As a result, many people choose to dispose of waste oil by burning it in order to generate heat for use in space heating, water heating or other general heating purposes in a residential or commercial environment. This is especially the case when referring to the higher volume producers of waste oils that wish to avoid the high cost of disposal. However, specialized waste oil burners can be expensive and cost prohibitive to many potential users. Furthermore, many of these potential users already employ the use of low viscosity heating oil burners, making the purchase of a specialized waste oil burning system unnecessarily redundant.
The present invention would overcome these drawbacks by providing an oil burning system capable of burning oils varying in viscosity from low viscosity heating oil to high viscosity waste oils. In an alternate embodiment, the present invention provides a modification means by which conventional heating oil burners can be retrofitted to accommodate higher viscosity and waste oil combustion. Use of the present invention will provide a safe, efficient, cost-efficient and environmentally sound method of waste oil disposal.
The majority of high viscosity and waste oil burners operate in a similar manner, according to a variety of widely accepted combustion control practices and principles. The waste oil is passed through a mechanical filtration device in order to remove any particulate matter suspended therein. The oil is then preheated in order to lower the viscosity of the fuel to a point where it can be effectively delivered to the combustion chamber. Once heated to the appropriate level, the oil is delivered to a nozzle by a pump of either positive or variable displacement. As the oil is sprayed through the nozzle it is atomized, that is mixed with air or steam in order to produce a fine mist of oil droplets, in order to achieve a complete and efficient oil burn. Atomization can be achieved in a variety of manners, including introduction of the atomizing media in the nozzle itself or by creating turbulence in the forced combustion air as it enters the combustion chamber and mixes with the fuel. The atomized fuel is ignited by constant-spark electrodes due to the fact that the fuel will not support self-sustained combustion. In order to compensate for the fact that waste oils can vary in viscosity, the preheating must be adjustable so as to allow the oil to be heated to the appropriate temperature. Control of the waste oil burners can be achieved by varying the volume of the fuel and air delivered to the combustion chamber, although most conventional waste oil burners do not provide any means to do so. Furthermore, the preheating of the waste oil must be adjustable to accommodate oils of varying viscosity.
While there are many existing designs for waste oil burning apparatuses disclosed throughout the art that generally fall within the aforementioned design criteria, they all suffer, alone or in combination, from a variety of problems associated with the use thereof.
Many conventional waste oil burners do not include a means by which to regulate the oil flow rate through the nozzle. Since oils of varying viscosity pressurized equivalently will flow at different rates, the result is that a high viscosity fuel will burn at a slower rate than a low viscosity fuel. Also, over-firing, which leads to overheating that could cause a fire or explosion, and under-firing, which causes decreased efficiency and poor emissions, cannot be prevented or otherwise controlled. In fact, many waste oil burner designs intentionally limit the oil flow rate in order to prevent over-firing, thus limiting BTU output. As a result, these devices are inflexible, limit the types of fuel that can be burned, and essentially prohibit the use of heating oil therein.
Waste oil burners require preheating in order to lower the viscosity of the fuel to a point where it will flow more freely and can be atomized more thoroughly. However, heating waste oil often leads to carbonization, commonly referred to as "sludging," wherein the oil assumes a thick, tar-like consistency that can clog delivery lines, nozzles, filtering screens and forms a thick buildup on the interior surfaces of the heating tank. As a result, the oil burning components must be routinely cleaned, often requiring the disassembly of the apparatus and producing prolonged down-time.
Most waste oil burners require the presence of an atomizing medium, usually compressed air or steam, that is introduced and mixed with the oil at the burner nozzle in order to produce well dispersed, fine fuel droplets. The use of atomizing media requires the incorporation of an external compressor, which adds to the overall costs of the unit and presents another mechanical piece of equipment that must be maintained.
In the ancillary art, there are several waste oil burning devices that are considered related, but exhibit the aforementioned problems towards which the present invention is directed and solves.
Several patents disclose oil burners and/or nozzles, for use with heating oils, fuel oils, and heavy or waste oils, that utilize a variety of atomization configurations and mediums:
U.S. Pat. No. 1,428,896, issued in the names of McDonald and Haynes, discloses a fuel oil burner nozzle design that incorporates the use of pressurized steam as an atomizing medium. U.S. Pat. Nos. 4,141,505 and 4,249,885, both issued in the name of Reich, disclose a heavy fuel oil burner nozzle design that incorporates the use of a pressurized atomizing fluid, introduced to the fuel stream at a right angle in order to produce a shearing force that will produce enhanced atomization. U.S. Pat. No. 5,000,677, issued in the name of Lathion et al., discloses an atomizing liquid fuel burner design that incorporates the use of a pressurized air to atomize the fuel. U.S. Pat. No. 5,149,260, issued in the name of Foust, discloses an atomizing liquid fuel burner design that incorporates the use of a pressurized air to atomize the fuel. The Foust burner includes a complex circulation system for both the fuel and the atomization air in which both are preheated in order to enhance combustion. All of the above listed devices will require an external source for the pressurization and delivery of the atomization media which, as previously discussed, adds to the cost, complexity, and maintenance of the unit. Also, none of these patents disclose any means by which they can easily be cleaned of carbonization build-ups nor any means by which these build-ups are prevented.
U.S. Pat. No. 5,341,832, issued in the name of Foust, discloses an atomizing waste oil burner design that incorporates the use of a pressurized air to atomize the fuel. The burner nozzle design incorporated in this design includes a linearly actuated needle inside the discharge head of the nozzle that serves as a means by which to clean the injection orifice and to regulate the oil flow therethrough. This design also requires an external source for the pressurization and delivery of the atomization media which will add to the cost, complexity, and maintenance of the unit. Also, while this design does address the need to clean the injection nozzle, it does not address nor discuss any means by which to clean other burner assembly components such as filter screens, the nozzle interior housing, transfer or delivery lines.
U.S. Pat. No. 5,360,334, issued in the name of Kagi, Sr., discloses a waste oil burner that incorporates the use of a piston-pump for fuel delivery and atomization. The piston-pump delivers the fuel at an extremely high pressure, causing the fuel to atomize sufficiently when sprayed through the nozzle without the aid of any other atomizing media. The speed and stroke of the piston-pump are adjustable, allowing the fuel flow to be regulated in order to compensate for the flow characteristics of fuels of varying viscosity. While this invention addresses the problems associated with atomization media and the need to allow for variable fuel flow, it does not address the need to account for carbonization build-up. Also, the use of a piston-pump presents inherent difficulties in delivering the fuel at a constant flow rate due to the differential in pressures created between the forward stroke and back stroke of the piston.
U.S. Pat. No. 5,405,261, issued in the name of Scraggs, et al., discloses a waste oil heater, incorporating the use of an atomizing fuel nozzle, with an improved combustion chamber in which two firing stages help to ensure a more complete burn of the fuel. While this design very well may be an effective means to ensure a more complete burn, it does not address nor prevent the aforementioned problems associated with atomization media, fuel carbonization and the regulation of fuel flow rates.
U.S. Pat. No. 5,531,212, issued in the name of Smoker et al., discloses a multi oil furnace in which a conventional aspiration nozzle burner is incorporated into a combustion chamber designed to maximize heat transfer. Again, while this design very well may be an effective means to ensure a more efficient heat transfer, it does not address nor prevent the aforementioned problems associated with atomization media, fuel carbonization and the regulation of fuel flow rates.
While several features exhibited within these references are incorporated into this invention, alone and in combination with other elements, the present invention is sufficiently different so as to make it distinguishable over the prior art. Consequently, a need has been felt for a means by which oils, varying in viscosity from heating oil to heavy and waste oils, can be burned efficiently while minimizing or eliminating altogether the problems associated with the use of atomization mediums, the carbonization of the oil, and control of the flow rate through the burner nozzle.